Hm well this one seems like a practical issue. Either your client can wait a little more, and you go only when there are fewer people trying to get the vaccine, with the vaccines being very easily available, or find some other workaround instead of waiting, like... get information on when/where you can go and get the vaccine without having to be around a lot of other people indoors. Or maybe somewhere they are mostly waiting outdoors, which makes the risk nearly non-existent. Etc. These were just a few quick ideas. It just feels like to me, with this one, being solutions focused could help your worrying.